← All posts tagged Rust

O01eg
O01eg
coding Rust прекрасное О, clippy в стабильный компилятор завезли: blog.rust-lang.org
"cargo clippy

Speaking of warnings, you can now check out a preview of cargo clippy through Rustup. Clippy is a large number of additional warnings that you can run against your Rust code.

For example:

let mut lock_guard = mutex.lock();

std::mem::drop(&lock_guard)

operation_that_requires_mutex_to_be_unlocked();

This code is syntactically correct, but may have a deadlock! You see, we dropped a reference to lock_guard, not the guard itself. Dropping a reference is a no-op, and so this is almost certainly a bug.

We can get the preview of Clippy from Rustup:

$ rustup component add clippy-preview

and then run it:

$ cargo clippy
error: calls to `std::mem::drop` with a reference instead of an owned value. Dropping a reference does nothing.
--> src\main.rs:5:5
|
5 | std::mem::drop(&lock_guard);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: #[deny(drop_ref)] on by default
note: argument has type &std::result::Result<std::sync::MutexGuard<'_, i32>, std::sync::PoisonError<std::sync::MutexGuard<'_, i32>>>
--> src\main.rs:5:20
|
5 | std::mem::drop(&lock_guard);
| ^^^^^^^^^^^
= help: for further information visit rust-lang-nursery.github.io

As you can see from that help message, you can view all of the lints that clippy offers on the web.

Please note that this is a preview; clippy has not yet reached 1.0. As such, its lints may change. We’ll release a clippy component once it has stabilized; please give the preview a try and let us know how it goes."
O01eg
O01eg
coding Rust blog.rust-lang.org
"At long last, impl Trait is here! This feature has been highly desired for quite a while, and provides a feature known as “existential types.” It’s simpler than that sounds, however. The core of it is this idea:
...
Speaking of papercuts, since Rust uses the Result type for returning errors, and ? to make handling them easy, a common pain-point of new Rustaceans is to try and use ? in main:
...
Inclusive ranges with ..=
...
Another long-awaited feature is “slice patterns.” These let you match on slices similar to how you match on other data types."
O01eg
O01eg
Rust прекрасное @Strephil на заметку: habrahabr.ru
"По словам Грэйдона, язык получил название в честь грибов семейства ржавчинные, поскольку те являются «распределёнными организмами», не имеющими «единой точки отказа», и обладают исключительной живучестью. Такие грибы имеют пять стадий жизненного цикла и быстро прорастают. Хор решил, что это хорошая аналогия для ЯП, сфокусированного на безопасности и скорости работы."
O01eg
O01eg
coding Rust hg mercurial-scm.org
"Rust: implementation of `hg`

This commit provides a mostly-working implementation of the
`hg` script in Rust along with scaffolding to support Rust in
the repository.

If you are familiar with Rust, the contents of the added rust/
directory should be pretty straightforward. We create an "hgcli"
package that implements a binary application to run Mercurial.
The output of this package is an "hg" binary.

Our Rust `hg` (henceforth "rhg") essentially is a port of the existing
`hg` Python script. The main difference is the creation of the embedded
CPython interpreter is handled by the binary itself instead of relying
on the shebang. In that sense, rhg is more similar to the "exe wrapper"
we currently use on Windows. However, unlike the exe wrapper, rhg does
not call the `hg` Python script. Instead, it uses the CPython APIs to
import mercurial modules and call appropriate functions. The amount of
code here is surprisingly small.

It is my intent to replace the existing C-based exe wrapper with rhg.
Preferably in the next Mercurial release. This should be achievable —
at least for some Mercurial distributions. The future/timeline for
rhg on other platforms is less clear. We already ship a hg.exe on
Windows. So if we get the quirks with Rust worked out, shipping a
Rust-based hg.exe should hopefully not be too contentious."